Method for the ultrapasteurization of liquid whole egg products

ABSTRACT

Methods of ultrapasteurizing liquid whole egg products in continuous flow, high temperature, short time pasteurization equipment are provided. The equivalent point method is preferably used to evaluate the total thermal treatment received by the product in this equipment. Also disclosed is a method of making liquid whole egg products having preselected, extended, refrigerated shelf lives.

This application is a continuation of pending prior U.S. applicationSer. No. 07/535,718, filed June 11, 1990 now U.S. Pat. No. 4,994,291,which is a continuation of prior U.S. application Ser. No. 07/311,594,filed Feb. 16, 1989, now U.S. Pat. No. 4,957,759, which is acontinuation of prior U.S. application Ser. No. 06/904,744, filed Sept.8, 1986, now U.S. Pat. No. 4,808,425, issued Feb. 28, 1989.

DESCRIPTION OF THE INVENTION

The present invention relates to the pasteurization of liquid whole eggproducts generally, and particularly relates to ultrapasteurizationmethods which can be used to produce liquid whole egg products whichhave good functional properties and which have extended refrigeratedshelf lives.

BACKGROUND OF THE INVENTION

The U.S. egg industry produced more than 300 million pounds of frozenpasteurized egg products in 1985. The relatively mild pasteurizationprocesses used are designed to eliminate Salmonella from eggs for allpractical purposes, but do not destroy organisms capable of spoiling eggproducts held under refrigerated temperatures above freezing Thesurvival of spoilage organisms in pasteurized egg, coupled withconventional packaging technology, results in products with limitedshelf life (7-14 days at 40° F.) that require freezing and frozendistribution systems for preservation. Freezing is cost intensive,lowers the functional quality (flavor, performance, etc.) of the eggproduct, and results in an inconvenient product that requires thawingprior to use.

Standard pasteurization practices for liquid whole egg products aregenerally discussed in the Egg Pasteurization Manual (USDA AgriculturalResearch Service 1969). See also U.S. Pat. No. 3,949,099 to Kaufman, atcolumn 1, lines 46-58 (summarizing pasteurization processes). The EggPasteurization Manual notes that experiments conducted in England toestablish treatment conditions used there, which were carried out in ahigh temperature, short time pasteurization unit, included trials withholding times of two and one-half minutes and temperatures up to 151degrees Fahrenheit (66.1 degrees Centigrade). The functional quality ofthese eggs is not discussed; however, it is noted that England adopted alower temperature of 148 degrees Fahrenheit as a treatment condition.The Manual observes that such "severe" treatments help increase thestability of egg products in liquid form, but does not teach how thiscan be accomplished without sacrificing desirable functional propertiesof the products. For other types of egg products which are more heatstable, pasteurization temperatures as high as 152 degrees Fahrenheit(66.67 degrees Centigrade) have been reported. Again, little is knownabout how to ultrapasteurize (decrease the number of spoilagemicroorganisms to levels lower than obtained with a pasteurizationprocedure) these products by heating without sacrificing functionalperformance.

Higher temperatures than those investigated in England have beenexplored. See e.g., Essary, E. O., Rony, P. R., and Collins, W. F., Newuses of heated aseptically packaged fluid egg products, Report to theAmerican Egg Board (1983). This work suggested that merging techniquesof ultrapasteurization with aseptic packaging can be accomplished toyield safe, stable, and functional liquid whole egg. This researchsuggested and used a heat exchanger operated in laminar flow to processwhole egg at elevated temperatures, and used an ethylene oxide-flushedglove box to aseptically package the product (neither device approvedfor the commercial production of a salable product). Holdingtemperatures of up to 154 degrees Fahrenheit (67.8 degrees Centigrade)were reported. The results of this pioneering work demonstrated thepossibility of extending the refrigerated shelf life of liquid whole eggproducts, but did not enable the commercial production of a refrigeratedproduct which could be sold to consumers.

To carry out ultrapasteurization of liquid whole egg products oncommercial equipment, the time and temperature parameters of the thermaltreatment must be selected with care. Arbitrary increases in thermaltreatment will likely produce a functionally unacceptable product,or--even worse--coagulation of the product and blockage of thepasteurizing equipment. Because such pasteurizing equipment operates athigh pressures (e.g., 1,500 p.s.i. and more) the consequences ofblockage are serious. For these reasons, it is essential to know howliquid whole egg products respond to various thermal treatments beforeexperimenting with the production of these products on commercialequipment.

Because this essential information was not available, Hamid-Samimiinvestigated the time and temperature parameters which should be used incommercial equipment to obtain a functionally acceptable,ultrapasteurized, liquid whole egg product M. H. Hamid-Samimi, CriteriaDevelopment for Extended Shelf-Life Pasteurized Liquid Whole Egg. Ph.D.Thesis, North Carolina State University (1984). This research wascarried out at the laboratory bench, with a Brookfield viscometer, whichprocessed the product in small batches rather than continuously.Processing times and temperatures defining thermal treatments producinga soluble protein loss (SPL) of up to 5% from the product, as an upperlimit, were suggested as producing a functionally acceptable product.The suggested 5% SPL limit was defined by a graph line in the thesis:this line is reproduced herein in FIG. 3 as the 5% SPL (Batch) line.Time and temperature values tested by other investigators which werebelieved to be the limits of pasteurization are summarized in M. H.Hamid-Samimi and K. R. Swartzel, J. Food Processing and Preservation 8:219, 221 FIG. 1 (1984). All are below the 5% SPL (Batch) line.

The present inventors sought to test the predictions of Hamid-Samimi byultrapasteurizing liquid whole egg on continuous flow, high temperature,short time pasteurization equipment. It was unexpectedly found thatfunctionally acceptable liquid whole egg can be produced at times andtemperatures greater than previously believed. These findings, whichwill be explained in detail below, enable the commercial production offunctionally acceptable products with longer refrigerated shelf livesthan heretofore available. As will also be explained below, discovery ofthese unexpected results has led to the identification of several stepswhich should be taken to produce ultrapasteurized liquid whole eggproducts that have superior functional properties.

The object of the present invention, in short, is to provide liquidwhole egg products for refrigerated distribution which have greatlyreduced levels of spoilage microorganisms, while still having goodfunctional properties.

SUMMARY OF THE INVENTION

This object is achieved by a method for ultrapasteurizing liquid wholeegg products. The method comprises passing the liquid whole egg productas a continuous stream through a pasteurizing apparatus, during whichthe liquid whole egg product is heated to a predetermined realtemperature. The method is practiced so that the total thermal treatmentreceived by the liquid whole egg product is described by an equivalenttemperature and an equivalent time (these terms are explained in detailbelow) defining a point above the 5% SPL (Batch) line of FIG. 3, butinsufficient to cause coagulation of the product.

Also disclosed herein is a method of making a packaged liquid whole eggproduct characterized by a preselected refrigerated shelf life of fromabout four weeks to about 36 weeks. This method comprises passing theliquid whole egg product as a continuous stream through a pasteurizingapparatus, during which the liquid whole egg product is heated for apredetermined time and to a predetermined temperature. The predeterminedtime and the predetermined temperature are chosen to impart thepreselected shelf life to the liquid whole egg product. After it isheated, the liquid whole egg product is aseptically packaged.

Preferably, the continuous stream of liquid whole egg product referredto in each of the methods above is at least periodically subjected toturbulence while it is heated. The liquid whole egg products are also,preferably, homogenized after they have been heated. In addition, themethods described above are more narrowly described as methods in whichthe liquid whole egg product is heated to a predetermined holdingtemperature, then maintained at said predetermined holding temperaturefor a predetermined holding time, and then cooled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a continuous flow pasteurizingapparatus suitable for carrying out the present invention.

FIG. 2 is a diagram illustrating the differences and relations betweenreal holding times and holding temperatures, and equivalent times andequivalent temperatures for describing total thermal treatments, incontinuous flow pasteurizing equipment.

FIG. 3 is a graph showing time and temperature regions for theultrapasteurization of liquid whole egg products.

FIG. 4 is a graph showing equivalent times and equivalent temperaturesthat give particular refrigerated shelf lives for liquid whole egg.

FIG. 5 is a combination graph in which FIGS. 3 and 4 are superimposed,with the S. faecalis line removed

DETAILED DESCRIPTION OF THE INVENTION

Thermal treatments simultaneously produce beneficial and undesirablechanges in food products. Knowledge of kinetic methods, and how they canbe applied to the mechanics of designing a thermal process, aids inattaining food quality retention and process efficiency. Determining thetime and temperature requirement for a thermal process depends upondestruction of spoilage and disease causing microbial spores whileminimizing undesirable physical, chemical and biological transformationsthat occur within the product.

As schematically shown in FIG. 1, with arrowheads indicating directionof flow, continuous flow thermal processing equipment comprises heating,holding, and cooling sections The thermal treatment received by theproduct in the heating and cooling stage, (illustrated in FIG. 2), isoftentimes not considered instead, only the holding time (t_(H)) andholding temperature (T_(H)) are considered. However, when products arepasteurized in such equipment at higher temperatures and shorter times,as is taught herein, the contribution of the heating stage, and perhapsthe cooling stage, to the total thermal treatment of the product becomessignificant, and must be accounted for if a product with good functionalqualities is to be obtained and coagulation during pasteurization is tobe avoided. It is accordingly recommended that the equivalent pointmethod for evaluating thermal treatments be applied in practicing thepresent invention. As explained in detail below, this method describesthe total thermal treatment received by a product in continuous flowequipment with one equivalent time (t_(E)) and one equivalenttemperature (T_(E)) (see FIG. 2).

Procedures for use of the equivalent point method for analyzing thethermal effects on products during continuous flow heating have beenpreviously outlined (Swartzel, 1982, J. Food Sci. 47:1886 and Swartzel,1986, J. Agric. Food Chem 34:397) and are known to those skilled in theart This method differs substantially from previous methods in that allother methods define the thermal treatment based upon a single factorsuch as enzyme inactivation, microbial destruction, proteindenaturation, nutrient loss, etc. The problem with these other methodsis that a physical and/or chemical effect (flavor, color, productseparation and gelation during storage if thermally related) mayactually be the shelf life limiting factor.

The unique feature of the equivalent point method lies in the fact that,for any thermal curve, one equivalent time and equivalent temperaturecombination exists (see FIG. 2). This equivalent time and temperaturecombination will yield the exact thermal effect on all constituentswithin the product as would the original thermal curve. This unique timeand temperature combination is not dependent on individual constituentkinetics, as are all previous thermal evaluation procedures (it isindependent of constituent activation energy).

To determine the equivalent point of a thermal system, a completethermal history of the treatment must be available. This is obtained bymeasuring mixed mean product temperatures at various locations (entranceto the heat exchanger, exit of the heat exchanger and at least twolocations inside the heat exchanger). Time is calculated by correlatingmean residence time with location of the temperature probe. With heatexchangers into which it is difficult or impractical to insert thermalprobes, time-temperature curves are calculated based on knowledge of theproduct's physical characteristics and on the geometry of the processingequipment.

With available time-temperature curves and a basic knowledge of kineticrelationships, equivalent points can routinely be calculated. The log ofa product constituent concentration ratio (initial concentration dividedby concentration after treatment) is set equivalent to the integrationof that constituent's Arrhenius equation (or any other appropriatefunction describing the temperature dependency of the rate of thereaction associated with the constituent change) for the particulartime-temperature interval (thermal history previously defined) For agiven activation energy each section of a thermal treatment (heating,holding, and cooling) will produce a unique thermal constituentconcentration ratio For the different sections the effect may be summedFor the original activation energy selected, a linear infinite log(time)-temperature relationship exists. Any and all of these infinitetime and temperature combinations would produce the same thermal effecton a constituent (with the same activation energy) as during theoriginal thermal treatment. By reexamining the original thermal curveswith different activation energies a series of infinite linear log(time)-temperature relationships are developed (one line in a log(time)-temperature plot per activation energy). Uniquely all linesintersect at one point. This unique time-temperature is the equivalentpoint for the original thermal curve. It accounts for all thermaltreatment and is used to accurately predict constituent change, orproduct characteristic.

FIG. 3 sets forth thermal treatments which should be used toultrapasteurize liquid whole egg products. Thermal treatments defined bypoints above the 5% SPL (Batch) line have not heretofore been suggested.For practicing the present invention in continuous flow processingequipment, the thermal treatment is described by a point on FIG. 3defining an equivalent time and an equivalent temperature, as explainedabove. The thermal treatment should be more than sufficient topasteurize the liquid whole egg product "Pasteurize" means to cause anine log cycle (9D) or 99.9999999% reduction in Salmonella in theproduct being treated. The thermal treatment should be insufficient tocause the liquid whole egg product to coagulate. The thermal treatmentshould more particularly cause not more than a 15% soluble protein loss(SPL) in the liquid whole egg product being treated, and will preferablycause not more than a 5% soluble protein loss in the product beingtreated. The expected 5% SPL (continuous processing) line on FIG. 3indicates approximately the upper limit on thermal treatments which canbe tolerated without sustaining more than a 5% soluble protein loss (theexact location of this line for any one process will depend on thephysical factors discussed below). More preferably, the thermaltreatment will be designed to produce not more than about a 1% solubleprotein loss from the product. As shown in FIG. 3, equivalent times andequivalent temperatures defining points along the line previouslybelieved to represent the line at which a 15% soluble protein loss wouldbe obtained (the 15% SPL (Batch) line), are now known to representthermal treatments which produce ultrapasteurized products having lessthan a 1% soluble protein loss under continuous flow.

The line defining thermal treatments causing a seven log cycle reductionin the spoilage bacteria Streptococcus faecalis is labeled in FIG. 3 asthe S. faecalis (7D) line. The S. faecalis line has a steeper slope thanthe several SPL lines. This illustrates that thermal treatmentsemploying higher temperatures and shorter times are preferred forpracticing the present invention. Thus, holding soluble protein lossconstant (so that treatment time must be decreased as treatmenttemperature is increased), thermal treatments in which the product issubjected to treatment temperatures of about 67.0 degrees Centigrade ormore are preferred to thermal treatments in which the product issubjected to treatment temperatures of 65° C.; treatment temperatures ofabout 69.0° C. or more are preferred to treatment temperatures of 67° C;treatment temperatures of about 71.0° C. or more are preferred totreatment temperatures of 69° C.; treatment temperatures of about 73.0°C. or more are preferred to 71° C.; and so on. The foregoing statementis true whether the real temperatures (or holding temperatures) of theprocesses are being compared, or equivalent temperatures are beingcompared (thus the term "treatment temperature" is used to encompassboth).

Treatment temperatures are primarily limited by the ability toaccurately time the duration of the thermal treatment: as temperature isincreased the treatment time must be decreased, and shorter treatmenttimes are more difficult to administer with precision. Generally,equivalent temperatures not more than about 90° C. are preferred, andequivalent temperatures not more than about 80° C. are more preferred.

Desirable thermal treatments for practicing the present invention canalso be described with reference to the S. faecalis lines. Preferably,the thermal treatment will define a point above the S. faecalis (7D)line, and more preferably the thermal treatment will define a pointabove the S. faecalis (9D) line. While this latter line is not plottedin FIG. 3, it can be plotted in accordance with the equations givenbelow.

Equations for lines in the figures are as follows, where t=time inseconds, T=temperature in degrees Centigrade, and n=number of decimalreductions. Salmonella line: log(t)=15.96-0.227(T). S. faecalis lines:log(t)=24.62+log(n)-0.346(T). % SPL lines: log(t)=10 g(% SPL)=9-b, wherea and b are given in Table 1 below:

                  TABLE 1                                                         ______________________________________                                                    a (for            a (Expected)                                                Batch             (for continuous                                 T range °C.                                                                        lines)     b      flow lines)                                     ______________________________________                                          60-62.5   7.494      0.091  8.761                                           62.5-67.5   4.103      0.037  5.370                                           67.5-72.5   14.68      0.194  15.942                                          72.5 and above                                                                            3.014      0.033  4.281                                           ______________________________________                                    

These equations can be used to extend the teaching of the figures beyondtheir depicted scope.

The liquid whole egg product is preferably heated by contacting theproduct to a heated surface. The heated surface is comprised of acorrosion-resistant, nontoxic and nonabsorbent material such asstainless steel. Standards for evaluating the acceptability of suchproduct contact surfaces (the 3-A Sanitary Standards) are known andestablished. See, e.g. Egg Pasteurization Manual, supra, at 27.

To obtain a product with reduced amounts of spoilage microorganisms, thepasteurizing apparatus should be sterilized before the liquid whole eggproduct is passed therethrough. Sterilizing is preferably accomplishedby passing hot water under pressure through the pasteurizing apparatus,as is known in the art, so that, among other things, hot water iscontacted to the heating surface at a temperature and pressure and for atime sufficient to sterilize the heating surface.

In addition, the product, after ultrapasteurization, should beaseptically packaged Aseptically packaged means packaged to theexclusion of microorganisms other than those carried by the liquid wholeegg product. Equipment suitable for aseptically packaging liquid wholeegg products is commercially available.

FIG. 4 illustrates the refrigerated shelf life of liquid whole egg afterit is ultrapasteurized and aseptically packaged, as explained above Theterm "refrigerated," as used herein, means stored at a temperature of 4°C. Time and temperatures for points on each line represent equivalenttimes and temperatures, as also explained above. A liquid whole eggproduct having a preselected shelf life of from about 4-36 weeks is madeby selecting a point on a line or in a region which will provide thedesired shelf life, determining the equivalent time and equivalenttemperature which correspond to the point selected, and--preferablythrough the use of the equivalent point method--establishing theoperating conditions on the particular pasteurizing apparatus being usedthat will provide the selected thermal treatment. Products having shelflives not depicted in FIG. 4 are made by extrapolating the teachings ofthe figure, in light of the teachings above. Preferably, this process iscarried out in pasteurizing apparatus which has been sterilized beforethe liquid whole egg product is passed therethrough, as explained above,to produce products having shelf lives of about eight weeks or more. Inaddition, it will be appreciated that longer shelf lives are generallyobtained at the expense of greater levels of soluble protein loss. Thus,if product distribution systems do not require otherwise, products withshelf lives of up to about 32 weeks are preferred, and products withshelf lives up to about 24 weeks are more preferred.

FIG. 5 combines portions of FIGS. 3 and 4. It shows how the thermaltreatments selected to provide a desired shelf life can at the same timebe selected to provide products with good functional properties. Moreparticularly, thermal treatments can be selected which produce liquidwhole egg products having the desired shelf life and a soluble proteinloss not greater than 5%.

The foregoing graphs have been presented to aid the understanding of thepresent invention. Some variation about the plotted lines is to beexpected when the present invention is practiced on different equipment,or with different products. These graphs are accordingly not to be takenas limiting the present invention, as departures could be made therefromwhile still capturing and benefitting from the teachings of theinvention.

To obtain a superior ultrapasteurized liquid whole egg product, thecontact time of the liquid product to heated surfaces duringpasteurization should be reduced. More particularly, every particle ofliquid whole egg product should be in contact with the heated surface orsurfaces of the unit in which the product is heated for a total timeless than the residence time of the particle in the heating unit. (Theterm "particle" as used herein has its standard meaning in the eggpasteurization field. See, e.g., 7 C.F.R. § 59.570(b) (1985)). This isaccomplished by mixing the product at least periodically while it isbeing heated. In a continuous flow pasteurizing apparatus, such mixingis accomplished by introducing turbulence into the stream of the productat least periodically while it is being heated, as discussed below Othersteps which are preferably employed to reduce fluid element contact timeto heated surfaces include providing portions of the thermal treatmentin which fluid elements are not in contact with heated surfaces, such asby providing a portion of the thermal treatment in a holding section,and by providing heated contact surface area to product volume ratios ofless than 18 cm² /cm³ (Thus the surface area to volume ratio ispreferaby less than about 10, and is more preferably in the area ofabout 2).

It is also desirable to induce physical forces to make the product morehomogeneous prior to thermal treatment, such as by inducing shear forcescapable of reducing protein and fat unit size. This is preferablyaccomplished by dispersing the product prior to heating. Dispersing maybe carried out with a dispersing valve or with a timing pump, as isknown in the art. Such treatment advantageously reduces fouling, andserves to reduce any tendency of the product to coagulate. Such adispersing step may be carried out by conducting a more rigoroushomogenization step, but it is recommended that such more expensivehomogenizing equipment be used as described below.

It is preferable that a homogenization step after heating be included.The term "homogenized," as used herein, means to subject the product tophysical forces to reduce particle size. Such procedures are known inthe art, and may be carried out on different types of equipment. It ispreferable to carry out this homogenizing step with homogenizingequipment at total pressures of about 1,000 p.s.i. or more. Pressures ofabout 1,500 p.s.i. or more are more preferred, and pressures of 2,000p.s.i. or more still more preferred.

Of these steps, it is particularly desirable to mix the liquid whole eggproduct at least periodically while it is heated. As noted above, incontinuous flow equipment mixing is carried out by at least periodicallysubjecting the stream of liquid whole egg product to turbulence while itis heated. Turbulence, which is the mixing of particles over thecross-section of the product stream, is discussed in the EggPasteurization Manual at pages 6-8. Such turbulence is characterized bya Reynolds number greater than about 2,300, and preferably greater thanabout 4,600. Commercial high temperature, short time pasteurizing unitsare available which at least periodically impart turbulence to thestream of product being pasteurized while the product is being heated.For the purposes of the present invention, greater levels of turbulenceare preferred. Thus the liquid whole egg product is preferably subjectedto turbulence for a major portion of the time it is heated. Plate heatexchangers, trombone heat exchangers, spiral heat exchangers, and scrapesurface heat exchangers are illustrative of the types of known heatexchangers which can be used to subject liquid whole egg products toturbulence while they are heated The physical forces induced in scrapesurface heat exchangers are generally thought of as "mixing," but theseexchangers induce turbulence at least in regions of the product stream,and are therefore considered to induce turbulence for purposes of thepresent invention.

Examples of whole egg products which can be pasteurized in liquid formby the method of the present invention include whole egg, fortifiedwhole egg (whole egg with added yolk), salt whole egg (e.g., salt 10%),sugar whole egg (e.g., sugar 10%), blends of whole egg with syrupsolids, syrups, dextrose and dextrins and/or gums and thickening agents,blends of whole eggs with less than 1% sugar and/or salt, scrambled eggmixes (for example, a mix of about 51% egg solids, 30% skim milk solids,15% vegetable oil and 1.5% salt), reduced cholesterol egg products andblends thereof, custard blends, and the like. Products which areextremely sensitive to thermal processing and which are particularlysuitable for ultrapasteurization by the present invention include, forexample, liquid whole egg and blends thereof (less than 2% added noneggingredients), fortified whole egg and blends thereof (24-38% egg solids,2-12% added nonegg ingredients), liquid salt whole egg, liquid sugarwhole egg, and other liquid whole egg blends which are 24-38% egg solidsand 12% or less of added nonegg ingredients. Terms used herein havetheir standard meaning in accordance with industry and regulatory usage.See, e.g.,7 C.F.R. § 59.570(b) (1985).

The invention having been explained in general terms above, thefollowing examples are provided to further illustrate the invention.

EXAMPLES 1-10

Raw Egg Product. Raw liquid whole egg was obtained from a local breakingplant (Gold Kist, Durham, N.C.). The egg was taken from their rawholding tank which was agitated to thoroughly blend approximately 30,000pounds of egg. The egg was manually filled into 13.6 kg (30 lb) metalcans and were kept refrigerated before being transported 13.2 km (20 mi)to our laboratory in an insulated truck. The egg was held overnight at4° C. (40° F.) or allowed to stand at room temperature for up to 12hours to achieve higher bacterial numbers.

Thermal Processes. The time-temperature processes used in this studywere designed to be equal to or more severe than minimum conditionsdefined by the 9D line for the destruction of Salmonella in whole egg(USDA, 1969) and within predetermined limits of denaturation of eggprotein defined as percent soluble protein loss (%SPL) by Hamid-Samimiet al., J. Food Sci. 49:132 (1984). The objectives of this design wereto provide Salmonella negative whole egg with a low number of survivingspoilage organisms while retaining adequate functional properties.

The thermal processing system used is outlined in FIG. 1. It consistedof a plate-type heat exchanger for preheat, various modifications of theNo-Bac Unitherm model XLV (Cherry Burrell Corporation, Cedar Rapids,Iowa) to achieve different holding times, an aseptic homogenizeroperated at 10.34 mPa (1,500 p.s.i.), and an aseptic packaging system(Model AB-3-250, Tetra Pak Inc., Dallas, Tex.). The flow rate was2.89×10⁻⁴ m³ /sec (275 GPH) with heating, holding, and cooling pipediameters of 12.45 mm ID (5/8" nominal) stainless steel.

Before each process the entire system was sterilized at 121° C. for 30minutes using hot water in the product section and steam in the heatingmedia section and then cooled. The product and heating mediatemperatures were recorded for evaluation of the thermal effect of theheating section and to determine the total thermal effects. (Swartzel,J. Agri. Food Chem. 34:396 (1986). The temperatures were measured usingType T thermocouples with an electronic data logger (Model 9302, MonitorLabs., Inc., San Diego, Calif.). Each thermocouple probe was scannedevery 30 seconds (one minute for process #1) and the readout sent to acomputer for analyses The specific locations of the thermocouples in thesystem were as described by Swartzel and Jones. Paper No. 84-6006 of theAmerican Society of Agricultural Engineers (1984).

Approximately one hour prior to initiation of each process, 408.2 kg(900 lb) of raw egg were transferred from the metal cans to a 568 1 (150gal) vessel (Creamery Package Mfg. Co., Chicago, Ill.) and then mixed atroom temperature with the stirring propeller at ca. 30 r.p.m. Thisvolume of egg required approximately 20 minutes to process, thereforethe last liter of egg was processed not later than 80 minutes afterbeing removed from the cooler. Nine processes designated 1, 2, 3, 4, 5,6, 7, 8, and 9 were run. Process 6 was repeated and designated 6.1. Theywere conducted two days apart on egg picked up on the same day. Egg forprocesses 6.1 to 9 were held at room temperature for not more than 12hours to achieve a higher initial microbial load. All egg incubated atroom temperature was chilled to 4° C. (40° F.) prior to processing.

After holding the egg at the scheduled process time and temperature andprior to packaging, the temperature was reduced to less than 10° C. (50°F.) in less than 26 seconds. Occasionally, due to technical difficultiesit was not possible to cool the processed egg to below 10° C. In thoseinstances the processed egg was moved into a freezer at -20° C. for 20minutes after packaging. The packaging material was a low oxygenpermeable laminate of polyethylene, paper, and aluminum foil formed into250 ml containers (Tetra Pak aseptic filler model AB-3). Each packagewas dated and coded so that egg processed in the first seven minutes,the second seven minutes, and the remaining time were numbered 1, 2, and3, respectively. The processed and packaged egg was held overnight at 4°C. (40° F.) prior to obtaining samples and being distributed for fourand 10° C. storage.

Sampling Samples of raw egg for physical, chemical, and functionaltesting were aseptically removed from the mixing vat approximately 30minutes prior to processing. The samples were then held overnight at 4°C. for evaluation with the pasteurized egg. Pasteurized samples wereobtained on the day after processing or at selected times during storageat four and 10° C. Analyses were made on the combined contents of threeor four individual packages representing the first, second, and thirdportions of each process run. When four packages were required, twopackages from the middle portion of each process were used. Any sedimenton the bottom of the cartons was scraped out and mixed into the egg bymagnetic stirring.

Chemical Assays. The pH of the product was determined with a FisherAccumet pH meter, model 600, equipped with a calomel reference and glassindicating electrodes. Solids were determined in triplicate by weighingtwo ml samples into disposable aluminum pans and drying in a forceddraft oven for 24 hours. The AOAC (1985) microKjeldahl procedure wasused to determine protein content of the samples. The extent ofdenaturation was estimated by determining the loss of soluble protein asdescribed by Hamid-Samimi et al., supra, and the alpha-amylase activityof the egg was determined as described by Shrimpton and Monsey, J. Hyg.60:153 (1962).

Sponge Cakes. True sponge cakes were made by using half of the amountsof ingredients listed following the procedures given by Gorman and Ball(1986) (Chapter 15 in Egg Science and Technology, 3rd Ed., W. J.Stadelman and O. J. Cotterill, Eds., AVI Publishing Co., Inc. Westport,Conn.) with the omission of vanilla. Two separate batches of batter weremixed for each treatment and 340 g of batter was weighed intorectangular pans (21.5×11.5×6.5 cm, id.). Cakes were baked at 191° C.for 25 minutes, inverted on a wire rack and allowed to stand at roomtemperature overnight. Heights were determined from the mean of fourmeasurements along the center line of the long axis of the cake. Cakeswere then kept in plastic bags for further rheological evaluations.

Textural properties of the cakes were evaluated using an InstronUniversal Testing Machine (Model 1122, Instron Engineering Corporation,Canton, Mass.). A plate was connected to a 2000-g load cell andpositioned at the surface of the 5-cm cube of cake. The cross head andchart speeds were 200 mm/min and 100 mm/min, respectively. Three samplesfrom each cake were subjected to deformation-relaxation cycles. Thecubed cake samples were kept in a plastic bag before and after eachtest. The water activity of the cake samples were determined by placingthree Durotherm (Lufft, West Germany) water activity meters in theplastic bag. Each meter was calibrated daily with a solution of bariumchloride (aW 0.90 at 20° C.).

Custards. Duplicate custards of the flan type were made. Ingredientswere 190-ml evaporated milk, 196-g sweetened condensed milk, 125-g wholeegg, 50-g water, and one teaspoon vanilla. All ingredients were blendedin a Waring blender at low speed for one minute and 360-g were weighedinto a rectangular pan (14.3×8.0×5.6 cm, id.) which had been sprayedwith "PAM" (Boyle-Midway, Inc., New York, N.Y.). Pans were placed in atray containing 2.5-cm water and baked at 191° C. for 40 minutes. Afterovernight storage at 10° C., height of the custard in the pan wasdetermined from the mean of three measurements made and with calipersalong the center line of the long axis of the custard. Custards wereremoved from the pan after the sides were loosened with a spatula andallowed to stand at room temperature for 45 minutes. Height was againdetermined and percent sag was calculated according to Gardner et al.Poultry Sci. 61:75 (1982) . Custards were stored in plastic bags at 10°C. for rheological evaluation.

The flat plate described above for evaluation of cake texture wasreplaced with a 10.5 mm diameter rod with a semispherical tip andforce-deformation curves to failure were obtained for each custard.Cross head speed was 100 mm/min and all other parameters were the sameas used in evaluations of the cakes Five values were averaged to obtainthe penetration force (Fl) for each custard.

Organoleptic Evaluation. Flavor of processed and stored egg wasevaluated by one judge using the USDA palatability score (LaboratoryMethods for Egg Products, USDA, Agricultural Marketing Service PoultryDivision, Grading Branch, Washington, D.C. 20250 (1984)).

Thermal Process. The process times and temperatures used in this studyare presented in Table 2.

                  TABLE 2                                                         ______________________________________                                        Actual, Equivalent Times and Temperatures,                                    Calculated Heating Value of Treatments and                                    Predicted % SPL Based on Heating Value.sup.a                                  Actual        Equivalent  Heating   Theoreti-                                 Proc. Time    Temp.   Time  Temp. Value.sup.b                                                                           cal                                 No.   (Sec.)  (°C.)                                                                          (Sec.)                                                                              (°C.)                                                                        (G × 10.sup.42)                                                                 % SPL.sup.c                         ______________________________________                                        1     26.2    63.7    30.4  63.1   6.1    0.52                                2     92.0    63.8    97.5  63.3  20.8    1.74                                3     192.2   65.3    192.4 65.1  72.8    5.97                                4      9.2    67.8    15.7  66.5   8.4    0.71                                5     56.9    68.2    63.0  67.5  44.6    3.70                                6     123.0   68.3    125.5 67.9  99.4    8.10                                  6.1 123.0   68.9    129.0 68.4  117.6   9.50                                7      2.7    71.5     9.5  68.5   8.9    0.75                                8     30.1    72.2    36.5  71.5  78.9    6.46                                9     56.7    72.0    62.5  71.8  146.8   11.70                               ______________________________________                                         .sup.a See Swartzel, J. Food Sci. 47:1886 (1982), and HamidSamimi et al.,     supra (1984) for descriptions of heating value and % SPL.                     .sup.b G values are determined based on activation energy for SPL.            .sup.c Based on laboratory batch data.                                   

The 10 processes, numbers 1-9, were performed in the same chronologicalorder as they are numbered. After gaining process experience and as theresult of evaluations during the study, it was determined that longerholding times and temperatures than expected could be used. The actualtemperatures reported in Table 3 are the averages of temperaturereadings, every 30 seconds, of the temperature probes at the beginningand end of the holding tube.

Equivalent times and temperatures as well as holding times andtemperatures are set forth in Table 2. It can be seen that equivalenttimes are generally longer than the corresponding holding times, andequivalent temperatures are generally lower than the correspondingholding temperatures. At longer times, the differences betweencorresponding holding temperatures and equivalent temperatures aresmaller.

The calculated heating value, G, shown in Table 2, gives a means formaking a comparison of the relatively severity of the differentprocesses. Processes 9, 6.1, 6 and 8 had the highest G values,respectively. The percent SPL based on the heating value (G) are alsoshown in Table 2.

Chemical Properties of Processed Egg. The results of alpha-amylaseactivity assays (Table 3) confirms that the enzyme is inactivated bymild heat processes. Table 3 shows that the thermal processes used didnot affect protein content or the soluble protein content.

                  TABLE 3                                                         ______________________________________                                        Thermal Effects on Alpha-Amylase Activity,                                    Protein Content and % Soluble Protein                                                                            % Soluble                                                                     Protein.sup.c                              Process                                                                              Alpha-Amylase.sup.a                                                                         MicroKjeldahl.sup.b                                                                         (From Ab-                                  No.    Raw    UHT     Plant                                                                              Raw  UHT   Plant                                                                              sorbance)                          ______________________________________                                        1      0.045  0.048   0.099                                                                              13.10                                                                              11.60 13.1  86.2                              2      0.033  0.588   --   12.59                                                                              11.96 --   102.3                              3      0.055  1.050   --   11.67                                                                              11.32 --   101.3                              4      0.029  0.031   0.137                                                                              11.83                                                                              11.79 11.51                                                                              101.1                              5      0.046  1.000   --   10.19                                                                              10.13 --   100.3                              6      0.053  1.120   --   12.27                                                                              12.34 --   100.9                                6.1  0.040  1.130   --   12.70                                                                              12.54 --   103.3                              7      0.052  0.764   --   12.37                                                                              12.53 --   104.5                              8      0.063  1.000   --   11.19                                                                              11.42 --   100.4                              9      0.060  1.170   --   11.74                                                                              11.77 --   100.7                              ______________________________________                                         .sup.a AlphaAmylase data is reported as the absorbance at 585 nm. Activit     is inversely related in absorbance.                                           .sup.b MicroKjeldahl data is reported as percent protein.                     .sup.c Absorbance at 280 nm of heated egg/control (raw) egg in solution a     described by HamidSamimi et al., supra (1984).                           

The chemical data indicate that the processes did not result inextensive damage to the egg proteins. The predicted percent solubleprotein losses (Table 3) were based on studies conducted with smallamounts of egg (1 ml) being heated in the cup of a brookfield viscometer(Hamid-Samimi et al., supra, 1984). The egg was heated while variousshear rates were applied to simulate egg under dynamic conditions thatexist in conventional heat exchangers. Thus, this work revealed that themodel system resulted in prediction equations that underestimated thethermal treatments that liquid whole egg products could tolerate whilestill obtaining products with good functional properties. Analysis ofthe causes of these unexpectedly good results led to the guidelinesdiscussed above which should be followed to obtain functionally superiorultrapasteurized products.

Function of Processed Eggs. The functional properties of the processedeggs agreed with the physical and chemical results. Based on the datapresented in Tables 4 and 5 for nonstored egg, there appeared to be verylittle heat effect on the performance of the ultrapasteurized eggrelative to raw or commercially pasteurized egg. Cake height as anindication of the leavening ability and force to deform, springiness,and relaxation parameter (Peleg and Normand, Rheologica Acta 22:108(1983)) as indicators of textural properties were very similar for allegg examined.

                  TABLE 4                                                         ______________________________________                                        Functional Properties of Cakes for Control (Raw),                             Ultrapasteurized (UP) at Zero Day Storage, and                                Commercially Pasteurized Eggs (Plant)                                                  Treat-                                                               Variable ment    Mean    Minimum                                                                              Maximum n   C.V.                              ______________________________________                                        Maximum  Raw     10.02   7.79   13.70   10  17.3                              Force.sup.a                                                                            UP      10.49   9.18   12.91   10  10.5                              (N)      Plant   9.73    9.56   9.91     2  2.5                               Relaxa-  Raw     0.394   0.379  0.417   10  3.24                              tion.sup.b                                                                             UP      0.410   0.395  0.442   10  3.34                              Para-    Plant   0.402   0.402  0.403    2  0.17                              meter                                                                         Spring-  Raw     0.83    0.81   0.86    10  1.94                              iness.sup.c                                                                            UP      0.83    0.81   0.87    10  2.47                                       Plant   0.82    0.81   0.82     2  1.32                              Cake     Raw     65.1    63.3   66.7    10  1.66                              Height   UP      61.7    55.1   65.5    10  5.26                              (mm)     Plant   64.8    64.7   64.8     2  0.11                              Water    Raw     0.873   0.832  0.891   10  2.53                              Activity UP      0.875   0.835  0.892   10  2.37                                       Plant   0.892   0.892  0.892    1  --                                ______________________________________                                         .sup.a Force required to deform the sample of cake by 26 mm.                  .sup.b Asymptotic relaxation value as defined by Peleg and Normand, supra     (1983).                                                                        .sup.c Ratio of the second peak force to the first peak force in the         force deformation cycle.                                                 

                  TABLE 5                                                         ______________________________________                                        Functional Properties of Custards for Controls                                (Raw), Zero Day Storage Ultrapasteurized (UP)                                 and Commercially Pasteurized Eggs (Plant)                                              Treat-                                                               Variable ment    Mean    Minimum                                                                              Maximum n   C.V.                              ______________________________________                                        Penetra- Raw     0.82    0.76   0.96    10  8.20                              tion     UP      0.70    0.59   0.80    10  8.56                              Force    Plant   0.79    0.77   0.81     2  3.69                              (N)                                                                           Custard  Raw     35.7    35.1   36.7    10  1.66                              Height   UP      35.6    35.1   36.3    10  5.26                              (mm)     Plant   34.6    34.0   35.3     2  0.11                              % Sag    Raw     7.2     5.65   9.54    10  16                                         UP      7.1     5.41   8.56    10  13                                         Plant   4.6     2.66   6.51     2  59                                ______________________________________                                    

The water activity of the cakes were similar indicating that theexperimental handling procedures for the cakes were uniform and shouldnot have affected the instrumental evaluation of textural properties.The custard data indicated that all egg sources evaluated had goodability to form gels. The gels had excellent integrity as indicated bythe relatively low percent sag, yet the custards were relatively tenderas indicated by the penetration forces. Although weep was not measured,very little syneresis was noted even after holding the custardsovernight for textural evaluations. The limited organoleptic evaluationof the processed eggs indicated that the thermal processes did notaffect flavor or aroma in scrambled eggs relative to scrambled egg madefrom a fresh shell egg. The USDA palatability scores were seven to eight(eight being the highest score).

Refrigerated Storage Effect. As long as the processed egg was notobviously spoiled, as indicated by organoleptic evaluations, storage at4° C. maintained the chemical, functional, and organoleptic propertiesof the processed egg up to 24 weeks for some of the samples. The datapresented in Tables 6, 7, and 8 were taken from stored egg that wasjudged organoleptically sound. The criteria for that judgment were: (1)that the color was normal, i.e., within the expected range of colorobserved for eggs immediately post-processing, and (2) that there wereno objectional aromas or flavors. In this study, because of the samplingprocedure where most of the samples were checked at four-week intervals,there were no borderline decisions, a sample was obviously acceptable orunacceptable. Bright yellow colors, off-aromas, and pH values belowseven were typical of samples judged to be spoiled.

                  TABLE 6                                                         ______________________________________                                        Means for Proteins, Solids and pH for Controls                                (Raw), Commercially Pasteurized (Plant) and                                   Ultrapasteurized (UP) Egg                                                              Treat-                                                               Variable ment.sup.a                                                                            Mean    Minimum                                                                              Maximum n   C.V.                              ______________________________________                                        %        Raw     11.92   10.19  13.10   10  6.8                               Protein  Plant   12.30   11.51  13.10    2  9.1                                        UP 0    11.74   10.13  12.54   10  6.0                               %        Raw     24.6    23.9   25.2    10  1.6                               Solids   Plant   24.8    24.4   25.2     2  2.5                                           0    24.5    24.0   25.0    10  1.3                                           4    24.4    24.0   24.9    10  1.3                                        UP 8    24.4    24.0   24.7     9  0.9                                          12    24.3    23.8   24.7     7  1.3                                          18    24.9    24.4   25.5     2  3.1                                          24    24.8    24.7   24.9     2  0.3                               pH       Raw     7.5     7.2    7.6     10  1.7                                        Plant   7.1     7.1    7.2      2  0.5                                           0    7.5     7.3    7.6     10  1.4                                           4    7.4     7.2    7.6     10  1.4                                        UP 8    7.4     7.3    7.5      9  1.2                                          12    7.3     7.2    7.4      7  1.2                                          18    7.4     7.4    7.4      2  0                                            24    7.4     7.4    7.4      2  0                                 ______________________________________                                         .sup.a Numbers indicate storage at 4° C. in weeks for processed        eggs.                                                                    

                  TABLE 7                                                         ______________________________________                                        Functional Properties of Cakes Made from Eggs                                 Stored at 4° C.                                                                Storage                  Maxi-                                        Variable                                                                              (Weeks)  Mean     Minimum                                                                              mum    n   C.V.                              ______________________________________                                        Maximum 4        9.78     7.90   14.95  10  21.3                              Force.sup.a                                                                           8        10.37    7.82   14.53  9   20.5                              (N)     12       11.29    8.84   14.28  7   18.2                                      18       11.42    10.32  12.53  2   13.6                                      24       10.53    9.57   11.49  2   12.9                              Relaxa- 4        .3937    0.3759 0.4167 10  3.7                               tion    8        .3876    0.3636 0.4132 9   3.9                               Para-   12       .3846    0.3717 0.4032 7   3.0                               meter.sup.b                                                                           18       .3788    0.3788 0.3788 2   3.1                                       24       .3745    0.3704 0.3788 2   1.5                               Spring-          0.829    0.799  0.853  10  1.7                               iness.sup.c                                                                           8        0.834    0.811  0.872  9   2.0                                       12       0.834    0.820  0.843  7   0.9                                       18       0.831    0.829  0.832  2   0.3                                       24       0.815    0.787  0.843  2   4.9                               Height  4        61       54     65     10  6.02                              (mm)    8        64       63     67     9   2.06                                      12       64       60     65     7   2.7                                       18       63       62     65     2   3.0                                       24       65       65     65     2   0.22                              Water   4        0.860    0.796  0.888  10  4.2                               Activity                                                                              8        0.884    0.868  0.900  9   1.1                                       12       0.879    0.844  0.896  7   2.0                                       18       0.872    0.872  0.872  1   --                                        24       0.879    0.876  0.882  2   0.4                               ______________________________________                                         .sup.a,b,c See Table 4 for definition of terms.                          

                  TABLE 8                                                         ______________________________________                                        Functional Properties of Custards Made from                                   Eggs Stored at 4° C.                                                           Storage                                                               Variable                                                                              (Weeks)  Mean    Minimum                                                                              Maximum n   C.V.                              ______________________________________                                        Pene-   4        0.68    0.47   0.77    10  12.7                              tration 8        0.70    0.64   0.76    9   9.1                               Force   12       0.75    0.57   0.83    7   20.3                              (N)     18       0.94    0.85   1.02    2   12.6                                      24       0.82    0.76   0.88    2   10.5                              Custard 4        35      34     36      10  2.4                               Height  8        35      34     36      9   1.6                               (mm)    12       35      35     36      7   1.2                                       18       36      36     36      2   0.4                                       24       35      35     35      2   1.0                               % Sag   4        7.1     3.0    11.6    10  38.1                                      8        5.9     3.5    7.5     9   20.5                                      12       6.5     4.6    8.0     7   19.5                                      18       7.2     6.4    8.1     2   15.9                                      24       6.6     4.9    8.2     2   36.0                              ______________________________________                                    

Visual observations of the interiors of opened packages revealed verylittle sedimentation during storage. A very thin layer of a fine, lightyellow, granular-like material was observed on the bottom of cartonsafter four weeks of refrigerated storage.

Shelf Life. The times of spoilage of egg from each trial are presentedin Table 9.

                  TABLE 9                                                         ______________________________________                                        Shelf Life for Liquid Whole Egg Stored at 4° C.                                      Shelf Life                                                             Process                                                                              (Weeks)                                                         ______________________________________                                               1      4-8                                                                    2       8-12                                                                  3      >12                                                                    4       8-12                                                                  5      >18                                                                    6      18-24                                                                    6.1  >24                                                                    7      12-18                                                                  8      20-24                                                                  9      18-20                                                           ______________________________________                                    

These data were used to generate the time and temperature guidelines setforth in FIG. 5.

The invention has been discussed with a degree of specificity above.This discussion has been provided for illustrative purposes only, withthe scope of the invention being defined by the following claims.

That what which is claimed is:
 1. A method of ultrapasteurizing a liquidwhole egg product, comprising passing the liquid whole egg product as acontinuous stream through a pasteurizing apparatus, during which theliquid whole egg product is(a) heated to a predetermined holdingtemperature by contacting said liquid whole egg product to a heatedsurface, then (b) maintained at said predetermined holding temperaturefor a predetermined holding time, and then (c) cooled, wherein the totalthermal treatment received by the liquid whole egg product is defined byan equivalent temperature and an equivalent time defining a point abovethe 5% SPL (BATCH) line of FIG. 3, but insufficient to cause coagulationof the liquid whole egg product, and then (d) aseptically packaged toprovide a packaged liquid whole egg product characterized by arefrigerated shelf life of about four weeks to about 36 weeks.
 2. Amethod according to claim 1, wherein said pasteurizing apparatus issterilized before said liquid whole egg product is passed therethrough,and wherein said packaged liquid whole egg product is characterized by apreselected shelf life of about eight weeks to about 36 weeks.
 3. Amethod according to claim 1, wherein said liquid whole egg product issubjected to turbulence for a major portion of the time said liquidwhole egg product is heated.
 4. A method of ultrapasteurizing a liquidwhole egg product, comprising passing the liquid whole egg product as acontinuous stream through a pasteurizing apparatus, during which theliquid whole egg product is heated to a predetermined real temperatureby contacting said liquid whole egg product to a heated surface while atleast periodically subjecting said continuous stream of liquid whole eggproduct to turbulence, wherein the total thermal treatment received bythe liquid whole egg product is described by an equivalent time and anequivalent temperature defining a point above the 5% SPL (BATCH) line ofFIG. 3, but insufficient to cause said liquid whole egg product tocoagulate, followed by aseptically packaging the liquid whole eggproduct to provide a package liquid whole egg product characterized by arefrigerated shelf life of about four weeks to about 36 weeks.
 5. Amethod according to claim 4, wherein said liquid whole egg product issubjected to turbulence for a major portion of the time said liquidwhole egg product is heated.
 6. A method according to claim 4, whereinsaid liquid whole egg product is dispersed before said liquid whole eggproduct is heated.
 7. The method according to claim 4, wherein saidpasteurizing apparatus is sterilized before said liquid whole eggproduct is passed therethrough, and wherein said packaged liquid wholeegg product is characterized by a preselected shelf life of about eightweeks to about 36 weeks.
 8. A method of ultrapasteurizing a liquid wholeegg product, comprising passing the liquid whole egg product as acontinuous stream through a pasteurizing apparatus, during which theliquid whole egg product is(a) heated to a predetermined holdingtemperature by contracting said liquid whole egg product to a heatedsurface while at least periodically subjecting said continuous stream ofliquid whole egg product to turbulence, then (b) maintained at saidpredetermined holding temperature for a predetermined holding time, andthen (c) cooled, wherein the total thermal treatment received by theliquid whole egg product is defined by an equivalent time and anequivalent temperature above the 5% SPL (batch) line of FIG. 3, butinsufficient to cause said liquid whole egg product to coagulate, andthen (d) aseptically packaged to provide a packaged liquid whole eggproduct characterized by a refrigerated shelf life of about four weeksto about 36 weeks.
 9. A method according to claim 8, wherein said liquidwhole egg product is subjected to turbulence for a major portion of thetime said liquid whole egg product is heated.
 10. A method according toclaim 8, wherein said liquid whole egg product is dispersed before saidliquid whole egg product is heated.
 11. A method according to claim 8,wherein said pasteurizing apparatus is sterilized before said liquidwhole egg product is passed therethrough, and wherein said packagedliquid whole egg product is characterized by a preselected shelf life ofabout eight weeks to about 36 weeks.
 12. A method of making a packagedliquid whole egg product characterized by a preselected refrigeratedshelf life of about four weeks to about 36 weeks, comprising passing theliquid whole egg product as a continuous stream through a pasteurizingapparatus, during which the liquid whole egg product is heated bycontacting said liquid whole egg product to a heated surface for apredetermined time and to a predetermined temperature while at leastperiodically subjecting said continuous stream of liquid whole eggproduct to turbulence, wherein the liquid whole egg product is heatedfor a predetermined time and to a predetermined temperature selected sothat the total thermal treatment received by the liquid whole eggproduct is defined by an equivalent time and an equivalent temperaturenot greater than the expected 5% SPL (continuous processing) line ofFIG. 3, and wherein said predetermined temperature and saidpredetermined time are chosen to impart said preselected shelf life tosaid liquid whole egg product, followed by aseptically packaging theliquid whole egg product.
 13. A method according to claim 12 whereinsaid pasteurizing apparatus is sterilized before said liquid whole eggproduct is passed therethrough, and wherein said packaged liquid wholeegg product is characterized by a preselected shelf life of about eightweeks to about 36 weeks.
 14. A method according to claim 12 wherein saidliquid whole egg product is subjected to turbulence for major portion ofthe time said liquid whole egg product is heated.
 15. A method of makinga packaged liquid whole egg product characterized by a preselectedrefrigerated shelf life of about four weeks to about 36 weeks,comprising passing the liquid whole egg product as a continuous streamthrough a pasteurizing apparatus, during which the liquid whole eggproduct is(a) heated by contacting said liquid whole egg product to aheated surface for a time sufficient to raise said liquid whole eggproduct to a predetermined holding temperature while at leastperiodically subjecting said continuous stream of liquid whole eggproduct to turbulence, then (b) maintained at said predetermined holdtemperature for a predetermined hold time, wherein said holdingtemperature and holding time are selected so that the total thermaltreatment received by the liquid whole egg product is defined by anequivalent time and an equivalent temperature not greater than theexpected 5% SPL (continuous processing) line of FIG. 3, and wherein saidholding temperature and holding time are selected to impart saidpreselected shelf life to said liquid whole egg product, and then (c)cooled, followed by (d) aseptically packaging the liquid whole eggproduct.
 16. A method according to claim 15, wherein said pasteurizingapparatus is sterilized before said liquid whole egg product is passedtherethrough, and wherein said packaged liquid whole egg product ischaracterized by preselected shelf life of about eight weeks to about 36weeks.
 17. A method according to claim 16 wherein said liquid whole eggproduct is subjected to turbulence for a major portion of the time saidliquid whole egg product is heated.
 18. A method according to claim 1,4, 8, 12, 16, wherein said liquid whole egg product is liquid whole egg.19. A method according to claim 1, 4, 8, 12, 16, wherein said liquidwhole egg product is a liquid whole egg blend which is about 24-38% eggsolids and about 12% or less of added nonegg ingredients.